1. Technical Field
The present invention relates to a vacuum pump and a mass spectrometer.
2. Background Art
In a mass spectrometer, a working pressure region varies among a plurality of analysis units. A vacuum pump formed with a plurality of suction ports has been known as a vacuum pump for such a mass spectrometer (see, e.g., Patent Literature 1 [JP-A-2014-1743]).
The vacuum pump described in Patent Literature 1 includes three pump stages. A first suction port is provided on a suction side of the first pump stage, a second suction port is provided between the first and second pump stages, and a third suction port is provided between the second and third pump stages.
In the vacuum pump formed with the suction ports, the first pump stage exhausts the gas having entered through the first suction port, and the second pump stage exhausts the gas having exhausted from the first pump stage and the gas having entered through the second suction port. Similarly, the third pump stage exhausts the gas having exhausted from the second pump stage and the gas having entered through the third suction port. For example, the volume of gas exhausted from the third pump stage is several to some dozen times as much as the volume of gas exhausted from the second pump stage.
Thus, in the case of the vacuum pump formed with the suction ports, each pump stage needs to be configured suitable for a suction pressure and exhaust volume required for respective pump stage.